1. Field of the Invention
The present invention relates to the design of Ethernet networks. More specifically, the present invention relates to a method and apparatus for multiplexing low-speed Ethernet channels onto a high-speed Ethernet link.
2. Related Art
In order to keep pace with increasing Internet traffic, optical fibers and associated optical transmission equipment have been widely deployed to substantially increase the capacity of backbone networks. However, this increase in the capacity of backbone networks has not been matched by a corresponding increase in the capacity of access networks. Even with broadband solutions, such as digital subscriber line (DSL) and cable modem (CM), the limited bandwidth offered by current access networks creates a severe bottleneck in delivering high bandwidth to end users.
Among the different technologies that are presently being developed, Ethernet networks are one of the best candidates for next-generation access networks. A combination of ubiquitous Ethernet technology with inexpensive high-speed optical transmission equipment is a very attractive solution. For example, Gigabit Ethernet (GbE) over an optical link offers the simplicity and scalability of Ethernet with the cost-efficiency and high capacity of passive optics. In particular, due to the high bandwidth of optical fibers, GbE networks are capable of accommodating broadband voice, data, and video traffic simultaneously. Furthermore, GbE networks are more suitable for Internet Protocol (IP) traffic, because Ethernet frames can directly encapsulate native IP packets with different sizes, whereas incumbent Asynchronous Transfer Mode (ATM) networks use fixed-size ATM cells and consequently require packet fragmentation and reassembly.
Typically, an Ethernet local area network (LAN) operates at a 10 Mbps or 100 Mbps data rate. Although GbE provides a cost-effective high-speed transmission solution, a single user most likely cannot fully utilize the entire bandwidth of an GbE link. Therefore, it is desirable to aggregate multiple low-speed Ethernet channels onto a high-speed Ethernet link. However, existing traffic aggregation techniques are based on packet-level multiplexing, which requires intensive processing and complicated software control. As a result, the costs of these packet-level-multiplexing solutions are quite high.
Hence, what is needed is a method and an apparatus for multiplexing low-speed Ethernet channels onto a high-speed Ethernet link without incurring much processing overhead.